from datetime import datetime, timedelta
from typing import Iterator

from fastapi import APIRouter, Depends, HTTPException, status

from .. import caldav_principal

router = APIRouter(prefix="/calendar", tags=["calendar"])


async def get_calendar_names() -> Iterator[str]:
    principal = caldav_principal()
    return (
        cal.name
        for cal in principal.calendars()
    )


@router.get("/list", response_model=list[str])
async def list_calendars(
    calendar_names: Iterator[str] = Depends(get_calendar_names),
) -> list[str]:
    return list(calendar_names)


async def find_calendars_by_prefix(
    prefix: str,
    calendar_names: Iterator[str] = Depends(get_calendar_names),
) -> Iterator[str]:
    return (
        name
        for name in calendar_names
        if name.lower().startswith(prefix.lower())
    )


@router.get("/find/{prefix}", response_model=list[str])
async def find_calendars(
    calendar_names: Iterator[str] = Depends(find_calendars_by_prefix),
) -> list[str]:
    return list(calendar_names)


@router.get("/get/{prefix}", response_model=list[str])
async def get_calendar(
    calendar_names: Iterator[str] = Depends(find_calendars_by_prefix),
) -> list[str]:
    calendar_names = list(calendar_names)

    if not (calendar_names):
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND)

    elif len(calendar_names) > 1:
        raise HTTPException(status_code=status.HTTP_409_CONFLICT)

    calendar = caldav_principal().calendar(name=calendar_names[0])

    events = calendar.date_search(
        start=datetime.now(),
        end=datetime.now() + timedelta(days=365),
        expand=True,
    )

    return list(
        str(child.contents['summary'][0].value)
        for event in events
        for child in event.vobject_instance.contents['vevent']
    )